This phase III randomized, double-blind clinical trial is designed to determine if Nevirapine, given to the mother during active labor and to the infant 48-72 hours after birth, can reduce the risk of prenatal transmission. HIV-1 infected pregnant women with estimated gestational age >-32 weeks will be enrolled. By accepting women who present late in pregnancy, this study does not conflict with the currently open study ACTG185, which requires enrollment of women by 30 weeks of gestation.